Tilt-actuated switch



- "Sept. '14, 1948. I L.IK. PERRY 2,449,177

TILT-AGTUATED SWITCH Filed-April 23,-1946 2 Sheets-Sheet 1 IN V EN TOR.

LESL/E K. PEPE) BY ATTORNEY Sept. 14, 1948. 1.. K. PERRY TILT-ACTUATED SWITCH 2 Sheets-Sheet 2 Filed A ril 23, 1946 INVENTOR. LESLIE K. PERRY ATTORNE Y i ate'n ted Sept. 14, 1943 U N! T ED STATES PATENT O-F F ICE lTllLT-A'CTUATED SWITCH Ircsiie Knllerry, 'LosAngeles, Calif.

,AplilicationlApfllifi, 194G, :Serial Nc. 1564247 1 r This invention :relates g'eneral'ly'to the art of navigation, and more particularly to apparatus for-automatically actuating flying controls "of an aircraft to maintain 'a predetermined flight course.

An object ofthi's invention "is'to'provide'an instrument of the above'described character, which is distinguished by its simplicity and compactness of construction, is relatively inexpensive to manufacture so as to enable'it "to'beinstalled in smaller planes at a comparatively low cost, and which, in its installed position, is

"adapted to control power-actuatedflyingfcontrol surfaces such as the trim 1 tabs "of the ailerons and elevators of the aircraft "ma-mannerfor the 'latter'to maintain level flight by'the'automa'ti'c correction of any deviationtherefrombothz longi- 'tudinally and laterally -of the aircraft.

set forth in the following specificationand particularly pointed out in the appended claims;

In the accompanyingdrawings,

Figure 1 is a view showing in verticalaxial section, oneformof automatic 'pi-lot embodying this invention Figure 2 is a horizontal sectional'viewtaken on the line 2-2 of Figure 1, and "lookinginthe "direction of the arrows; and

Figure 3 is a fragmentary horizontal sectional view of the switch mechanism,- taken on the line 3-3 of Figure 1 and diagrammaticallyincluding the ailerons and elevators with'the servomotors and electrical circuits therefor, "by which the *trim tabsare actuated.

Referring specifically to 'tl1e-drawings, theiinvention in its illustrated embodiment comprises 'a case designated generally at C and composed ofafioat chamber Ill and a switch compartment H. The float chamber is spherical and is divided diametrically into two semi-spherical portions l2 and I3 secured together by bolts '14 (Figure '1) passing through mating peripheral'flanges f5 and "It to clamp the portions together with a fluidtightjoint therebetween. The switch compart nion's '22 is operatively connected to an "adjusting knob 15 through an irreversible :worm and'wor'm wheel-drive 26, whereas one'of the trunnions20 is 'operatively connected to asimilar adjusting knob Zl-through an irreversible wormand worm wheel drive 28 and a flexible shaft2'9, all to'the end of facilitating adjustment of the case C to permanen'tly occupy a predetermined fixed position relative to the aircraft when the instrument is installed therein.

A float'designated generally at F comprises a spherical body 36 of balsa or otherslightwood or fluid-tight hollow sheet metal of an outside "di- 'ameter somewhat less than the diameter of the chamber It, to provide a fluid space 31 therebetween. At equally spaced intervals aroundthe periphery of the body 35 are bearing projections 32 semi-spherical attheir outer ends and'a'dapted to freely contact the wall of the chamber with minimum friction which is rendered negligible by filling all otherwise unoccupied space in*the chamber with a liquid substance suchas mercury 'orhydraulic brake fluid, to the'end that the coefficient of friction between the float and wall of the chamber will be extremely small. The float F maybe coated'with a suitable. liquid-proofpaint to render the float impervious to the liquidtbeing used in the chamber.

At its highest point, the chamber l'fiis provided with an inlet opening 35 into which is screweda nipple-$5 projecting from the "bottom "of an expansion chamber '3? to mpport same on the portion l2 of the case "C as shown in Figure 1. The expansion chamber '3liscprovided with a removable .filling plug 38 conta'ininga suitable ball check valve as which preven'tsfloss of liquid, lyet permits circulation of air'in. order to c prevent pressure from being built up in the float chamber/Ill.

.Theffloat 'F is o-peratively connected tofa switch mechanism S inthe compartment 'I l by. a motion transferring element in the form of a shaft "L which provides a'lever of the first class consisting of a fulcrum ball it and co-axially related cylindrical arms 4| and 42. The ball 40 is mounted in a socket bearing 43, one portion of which is formed in the flange I8 of the case part i3, and the other portion in a plate 44 secured in a counterbore in the flange I8 by screws 45, so as to mount the shaft L with its arm 4| projecting through a flaring bore 46 into the chamber I5, and its arm 42 projecting into the compartment I.

The arm 4| is telescopically received in one end of a connector sleeve 41 a rod 48 extends through a diametric bore 49 in the float body, and is provided at one end with a head 50, and at its other end is threaded to receive a nut to rigidly secure the rod against displacement. The head 50 is formed with a seat 52 for a ball 53 carried by said other end of the connector sleeve 41, said ball bein confined against the seat 52 by a nut 54 threaded on the head, all as clearly shown in Figure 1, and to provide a combined three hundred-sixty degree swiveling connection and an axially extensible connection between the float F and lever L.

The arm 42 of the lever L is threaded to rigidly mount thereon the electrical insulating body 55 of an annular contact element which constitutes the main contact 56 of the switch S, and is adapted for engagement with motor contacts 66, 6|, 62 and 63 of segmental form and grouped in a circular series around the contact 56 at ninety degree angular distances apart, with the two opposed forward and reverse motor contacts 66 and 6| being laterally offset from the other two opposed forward and reverse motor contacts 62 and 63, to permit the end portions of the contacts to be in circumferentially overlapped and insulated relation. The several contacts 60, GI, 62 and 63 are fixed in the slightly tapered bore 54 of a support 65 of insulating material secured in the switch compartment II to the flange l8 of the case C by screws 66. As shown in Figure 1, the contacts 66, 6|, 62 and 63 are secured to binding posts 61, 68, 69 and respectively, whereas the main contact 56 is connected directly by a conductor II and a flexible lead wire '52 to a grounded source of current supply 13.

Conductors l4 and I5 connect the binding posts 6'! and 68 of the respective contacts 60 and GI to a reversible electric motor 76, which, through cable and pulley connections I1 and 18 to the trim tabs 19 of the elevators 86 of the aircraft, is adapted to raise or depress the tabs according as upward or downward correction in a fore and aft direction is needed to maintain level flight. Conductors 8! and 82 connect the binding posts 69 and Ti] of the respective contacts 62 and 63 to a reversible electric motor 83, which, through cable and pulley connections 84 and 85 to the trim tabs 86 of the ailerons 87 of the aircraft, is adapted to reversely actuate the ailerons in one direction or the other according as right or left hand banking correction is required to maintain level flight, all as diagrammatically shown in Figure 3.

The operation of the invention is as follows:

The instrument is installed on the instrument panel 24 of the aircraft, and the case C adjusted in its mounting to dispose the main contact 56 centrally within and equally spaced radially from the motor contacts 60, 6|, 6-2 and 63 with the aircraft occupying a position corresponding to that of level flight in fore and aft and lateral directions.

With the aircraft in flight, any deviation of the craft from a level position will correspondingly tilt the case C in a fore and aft and/or lateral direction, whereas the float F will, by the action of gravity and the negligible friction between the float and case, tend to maintain a fixed relation to the earth, so that a predetermined angular movement of the case relative to the float will react through the lever L to engage the contact 56 with a contact 60, 6|, 62 or 63.

For example, should the aircraft assume a diving angle, the resulting forward tilting of the case C from its normal perpendicular position shown in Figure 1, will cause the contact 60 and contact 56 to engage and thus supply current to the motor 16 to drive same in such direction as will actuate the elevator trim tabs 19 to restore the aircraft to a level position, by completing an electrical circuit as follows:

From battery 13, conductors H, 12 to contact 56, contact E0, binding post 61, conductor 14 and motor 16 to the grounded side 01 the battery 13.

Should the aircraft assume a climbing angle, the resulting fore and aft tilting of the case 0 will engage the opposite contact 6| and the contact 56 to supply current to the motor 16 to drive same in the reverse direction so as to reversely actuate the trim tabs 19 to restore the aircraft to level position, by completing an electrical circuit as follows:

From battery 73, conductors H, 72 to contact 56, contact 6|, binding post 68, conductor I5 and motor 16 to the grounded side of the battery 13.

Should the aircraft assume a right or left hand banking angle, the contact 56 will accordingly engage the contact 52 or 63 to complete a circuit including the motor 83 through either the conductor 8| or the conductor 82 so as to drive the motor 83 in one direction or the other and accordingly actuate the trim tabs 86 of the ailerons 81 in the directions necessary to restore the aircraft to an even keel.

Should the aircraft assume a combined fore and aft and banking attitude, one of the contacts 60, GI and one of the contacts 62, 63 will engage the contact 56 so as to drive both motors 16 and 83 in the proper directions for the trim tabs 19 and 86 to be actuated in directions for them to co-act in restoring the aircraft to an even keel.

From the foregoing description, it will be manifest that any deviation of the aircraft from substantially level flight will be automatically corrected so as to greatly simplify the control of the aircraft by relieving the pilot of manual actuation of the controls, as well as the constant attention otherwise necessary to maintain the craft on an even keel. By looking the rudder of the craft in a precalculated position to fly a desired compass course, the duties of the pilot in controlling the flying control surfaces of the craft can be reduced to a minimum.

I claim:

1. In an instrument of the class described. means defining a chamber containing a liquid and adapted to be fixed to an aircraft; a buoyant body rotatable in said liquid and guided by the chamber wall with negligible friction; switch mechanism composed of a main contact and a plurality of motor contacts; means mounting said motor contacts in a circular series around the main contact, for unitary movement with the first means as the aircraft assumes various attitudes when in flight; a motion transferring element having a connecting portion and a portion carrying said main contact; means co-acting 5. with said element to mount same for tilting movements in any direction about a fixed ccnter on the first said means; and means co-acting with said connecting portion of said element and said body, to o-peratively connect them for tilting movement of the element to engage said main contact with a predetermined one of said motor contacts in accordance with the direction of the aforestated movement of the first said means.

2. In an instrument of the class described, a case having a chamber containing a liquid, and adapted to be fixed to an aircraft for movement therewith in assuming various attitudes when in flight; a buoyant body rotatable in said liquid; a plurality of segmental shaped motor contacts insulated from each other and supported in a circular series by the case, with the ends of adjacent contacts in circumferentially overlapped relation; a main contact; a motion transferring element having a connecting portion and a portion carrying said main contacts; means co-acting with said element to mount same for angular movement about a fixed center on the case; and means co-acting with said connecting portion of the element and said body, to operatively connect them for angular movement of the element to engage said main contact with a predetermined one of said motor contacts or with two thereof at their overlapped ends, in accordance with the direction of the aforestated movement of the case.

3. In an instrument of the class described, a case having a chamber containing a liquid, and adapted to be fixed to an aircraft for movement therewith in assuming various attitudes when in flight; a buoyant body rotatable in said liquid; a main contact; a lever having an arm supporting said main contact; means mounting the lever for universal angular movement about a fixed fulcrum on the case; a plurality of motor contacts supported by the case in a circular series about the main contact; and means operatively connecting the lever to the buoyant body to effect angular movement of the main contact about said fulcrum in a predetermined direction in accordance with the direction of the aforestated movement of the case, for engagement of the main contact and a predetermined motor contact.

4. In an instrument of the class described, a case having a chamber containing a liquid, and adapted to be fixed to an aircraft for movement therewith in assuming various attitudes when in flight; a buoyant body rotatable in said liquid; a main contact; a lever having an arm supporting said main contact; means mounting the lever for universal angular movement about a fixed fulcrum on the case; a plurality of motor contacts supported by the case in a circular series about the main contact; a connector having an axially extensible operative connection to a second arm of said lever; and a universal joint connection between said connector and said buoyant body for actuaton of the lever in a predetermined direction about said fulcrum, in accordance with the direction of the aforestated movement of the case.

5. In an instrument of the class described, a case having a chamber containing a liquid, and adapted to be fixed to an aircraft for unitary movement therewith in assum'ng various attitudes when in flight; a buoyant body rotatable in said liquid; a lever of the first class having a ball fulcrum mounted in said case below the chamber and having one arm projecting upwardly into the chamber; a main contact carried by the other arm of the lever below and exteriorly of the chamber; a plurality of motor contacts supported by the case in a circular series about the main contact for respective engagement therewith in response to movement of the lever about its fulcrum; and means operatively connecting said one arm of said lever to the buoyant body to actuate said lever and engage said main contact with one of said motor contacts in accordance with the direction of the aforestated movements of the case.

6. In an instrument of the class described, a case having a chamber containing a liquid, and adapted to be fixed to an aircraft for unitary movement therewith in assuming various attitudes when in flight; a buoyant body in said liquid; a lever of the first class having a ball fulcrum mounted in said case below the chamber and having one arm projecting upwardly into the chamber; a main contact carried by the other arm below and exteriorly of the chamber; a plurality of motor contacts supported by the case in a circular series about the main contact for respective engagement therewith in response to movement of the lever about its fulcrum; a connect-or sleeve telescopically receiving said one arm of the lever; and a ball and socket joint connecting said sleeve to the buoyant body for actuation of the lever in response to the aforestated movements of the case.

LESLIE K. PERRY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,203,221 Macy Oct. 31, 1916 1,274,333 Roland July 30, 1918 1,286,860 White Dec. 3, 1918 1,565,763 Vickers Dec. 15, 1925 1,579,370 Krammer Apr. 6, 1926 1,826,013 Meredith Oct. 6, 1931 1,859,752 Sperry May 24, 1932 1,881,137 Schneider Oct. 4, 1932 2,278,015 Openshaw Mar. 31, 1942 

